Data integrity protection in storage volumes

ABSTRACT

A plurality of logical volumes are stored at a plurality of sites. A command to execute an operation on a logical volume is received. A determination is made as to whether a rule associated with the logical volume permits execution of the operation on the logical volume. In response to determining that the rule associated with the logical volume permits execution of the operation on the logical volume, the operation is executed on the logical volume.

BACKGROUND

1. Field

The disclosure relates to a method, a system, and a computer programproduct for data integrity protection in storage volumes.

2. Background

A plurality of sites may be coupled together via one of more networks,wherein each of the plurality of sites may have one or more storagecontrollers that store data in storage volumes. Some of the sites may beseparated by extended distances, such as distances exceeding a thousandkilometer, whereas certain other sites may be relatively proximate toeach other. Data replication, i.e., copying of data, may be performedover extended distances between two or more sites for businesscontinuity and disaster recovery. In certain mechanisms, data may bereplicated synchronously or asynchronously. Additionally, in certainmechanisms, consistency groups of volumes may be formed at regularintervals in order to allow recovery of data.

The copy services functions performed in the plurality of sites mayinclude many types of operations. For example, point in time copyoperations may make it possible to create copies of entire logicalvolumes or data, nearly instantaneously. Peer to Peer Remote Copy orPPRC operations may make it possible to replicate a storage volume toanother control unit in a remote site, either synchronously orasynchronously. In certain computing environments a plurality of storagevolumes may be simultaneously copied from a primary site to a recoverysite, while maintaining point in time consistency across the pluralityof storage volumes.

SUMMARY OF THE PREFERRED EMBODIMENTS

Provided are a method, a system, and a computer program product in whicha plurality of logical volumes are stored at a plurality of sites. Acommand to execute an operation on a logical volume is received. Adetermination is made as to whether a rule associated with the logicalvolume permits execution of the operation on the logical volume. Inresponse to determining that the rule associated with the logical volumepermits execution of the operation on the logical volume, the operationis executed on the logical volume.

In additional embodiments, in response to determining that the ruleassociated with the logical volume does not permit execution of theoperation on the logical volume, the execution of the operation on thelogical volume is avoided.

In further embodiments, a determination is made as to whether aparameter of the command indicates that the rule associated with thelogical volume is to be overridden by the command. In response todetermining that the rule associated with the logical volume is to beoverridden by the command, the operation on the logical volume isexecuted.

In yet further embodiments, the rule associated with the logical volumerestricts a copy operation to be performed on the logical volume tooverwrite the logical volume if the logical volume stores a consistentcopy of another logical volume. Additionally, a label associated withthe logical volume identifies the logical volume.

In certain embodiments, the logical volume is a first logical volumethat is in a consistent copy service relationship with a second logicalvolume. The command is a withdraw command that requests withdrawal of atleast the first or the second logical volume from the consistent copyservice relationship. The withdraw command is rejected in response tointerpreting rules associated with the first or the second logicalvolume.

In further embodiments, prior to receiving the command to execute theoperation on the logical volume, a volume label for the logical volumeis set, and the rule is associated with the volume label.

In certain embodiments, the logical volume is in a copy servicerelationship with another logical volume.

In additional embodiments, the logical volume is configured to performmigration of data or disaster recovery.

BRIEF DESCRIPTION OF THE DRAWINGS

Referring now to the drawings in which like reference numbers representcorresponding parts throughout:

FIG. 1 illustrates a block diagram of a computing environment thatincludes a plurality of storage controllers controlling a plurality oflogical volumes at a plurality of sites, in accordance with certainembodiments;

FIG. 2 illustrates a block diagram that shows an exemplary copy command,in accordance with certain embodiments;

FIG. 3 illustrates a block diagram that shows a rules data structureassociated with a logical volume, in accordance with certainembodiments;

FIG. 4 illustrates a block diagram that shows how a secondary volume isrestricted from being used as the target of a subsequent point in timecopy operation, in accordance with certain embodiments;

FIG. 5 illustrates a block diagram that shows how a withdraw command isrejected, in accordance with certain embodiments;

FIG. 6 illustrates a flowchart that shows first operations performed inthe computing environment, in accordance with certain embodiments;

FIG. 7 illustrates a flowchart that shows second operations performed inthe computing environment, in accordance with certain embodiments

FIG. 8 illustrates a block diagram of a computational system that showscertain elements that may be included in the storage controllers of FIG.1, in accordance with certain embodiments.

DETAILED DESCRIPTION

In the following description, reference is made to the accompanyingdrawings which form a part hereof and which illustrate severalembodiments. It is understood that other embodiments may be utilized andstructural and operational changes may be made.

Associating Rules with Storage Volumes

Mechanisms are provided for maintaining data integrity in storagevolumes that may have been replicated, i.e., copied, across a pluralityof sites. Volume labels and rules are associated with storage volumes toplace restrictions on operations that may be performed on the storagevolumes. For example, if point in time copy operations have been used toconsistently copy a first set of volumes to a second set of volumes, andthe second set of volumes are expected to be used for data recovery,then the second set of volumes may be restricted from being overwrittenvia rules that are associated with the second set of volumes. As aresult, erroneous commands that attempt to overwrite the second set ofvolumes may be rejected. The rules associated with the volumes may alsorestrict or permit other types of operations. Additionally, labels maybe associated with the volumes to indicate the identity of the storagevolume and to indicate whether the storage volume has original data,copied data, etc.

Exemplary Embodiments

FIG. 1 illustrates a block diagram of a computing environment 100 thathas a plurality of storage controllers 102 a, 102 b, . . . , 102 n thatare located in a plurality of sites 104 a . . . 104 b, . . . , 104 n.The plurality of sites 104 a . . . 104 n may be separated by extendeddistances, such as distances of over a thousand kilometer, or may bemore proximate. For example, two sites may be in the same office complexin a first continent, whereas a third site may be in a second continent.The storage controllers 102 a . . . 102 n may be any suitablecomputational device including those presently known in the art, suchas, a personal computer, a workstation, a server, a mainframe, a handheld computer, a palm top computer, a telephony device, a networkappliance, a blade computer, a storage server, a storage controller,etc. In certain embodiments, the storage controllers 102 a . . . 102 nmay comprise cloud component parts included in a cloud computingenvironment.

The plurality of sites 104 a . . . 104 n are coupled via a network, suchas the Internet, or via some other type of network, such as a storagearea network, a local area network, a wide area network, etc. While asingle storage controller has been shown in each site, in alternativeembodiments a plurality of storage controllers may be present in eachsite.

A storage controller may control a plurality of logical volumes, whereina logical volume is a logical representation of a physical storagevolume that is used for storing data. For example, the storagecontroller 102 a may control the logical volumes 106 a . . . 106 p, thestorage controller 102 b may control the logical volumes 108 a . . . 108q, and the storage controller 102 n may control the logical volumes 110a . . . 110 r.

In certain embodiments, a label and one or more rules are associatedwith each logical volume. For example, the label 112 and the one or morerules 114 are associated with the logical volume 106 a. Other labels116, 120, 124, 128, 132 and rules 118, 122, 126, 130, 134 that areassociated with other logical volumes are also shown in FIG. 1. Thelabels 116, 120, 124, 128, 132 may also be referred to a volume labelsor logical volume labels.

The labels 112, 116, 120, 124, 128, 132 may provide information thatidentifies the logical volume. For example, label 128 associated withlogical volume 110 a may indicate that the name of the logical volume110 a is “C”.

The rules 114, 118, 122, 126, 130, 134 may indicate restrictionsassociated with selected logical volumes, wherein in certain embodimentsthe restrictions may indicate operations that may or may not beperformed on selected logical volumes. For example, the rules 130associated with logical volume 110 a may indicate that the logicalvolume 110 a may not be the target of another point in time copyoperation. If the logical volume 110 a already stores data copied via aprevious point in time copy operation, then performing another point intime copy operation with the logical volume 110 a as the target volumemay overwrite the previously stored data that may have to be used in thefuture for data restoration. Therefore, the rules 130 may restrict thelogical volume 110 a from being overwritten.

Therefore, FIG. 1 illustrates certain embodiments in which labels andrules are associated with logical volumes, to provide constraints on theoperations that may be performed on the logical volumes.

FIG. 2 illustrates an exemplary command 200, such as a point in timecopy command 200 that may be executed in the computing environment 100.The point in time copy command 200 may have parameters comprising asource logical volume 202, a target logical volume 204, and a logicalvolume rule override flag 206. The point in time copy command 200 is acommand to copy a source target volume to the target logical volume.However, if the logical volume rule override flag 206 is set to adefault value of “false”, then when the point in time copy command 200is executed the rules associated with the source logical volume 202 andthe target logical volume 204 are also processed to determine whetherthe point in time copy command will actually copy the source logicalvolume 202 to the target logical volume 204. For example, if the rulesassociated with the target logical volume 204 indicate that the targetlogical volume 204 cannot be the target of any further point in timecopy operations, then the point in time copy command 200 will notexecute to overwrite the target logical volume 204.

In certain embodiments, if a user sets the logical volume rule overrideflag 206 to “true” to indicate that rules associated with logicalvolumes should be overridden, then the point in time copy command 200 isexecuted to copy the source logical volume 202 to the target logicalvolume 204 irrespective of any restrictions placed by rules associatedwith the source logical volume 202 or the target logical volume 204.

Therefore, FIG. 2 illustrates certain embodiments in which commands onlogical volumes are executed in the computing environment 100 by takingaccount of rules associated with logical volumes, in response to settinga logical volume rule override flag to a default value of “false”. Ifthe logical volume rule override flag is set to “true” then the rulesassociated with logical volumes do not restrict the operation of thecommands executed with the logical volumes as parameters.

FIG. 3 illustrates an exemplary embodiment 300 that shows how the rulesassociated with a logical volume X 302 are maintained in a logicalvolume rules data structure 304. In an exemplary logical volume rulesdata structure 304, for a first type of copy operation 306, and a secondtype of copy operation 308, it is indicated whether it is possible forthe logical volume X 302 to be a source 310 or a target 312 volume. Forexample, the “not allowed” indication 314 in the logical volume rulesdata structure 304 may be interpreted to indicate (as shown viareference numeral 316) that the first type of copy operation 306 is notpermitted where the target of the first type of copy operation is thelogical volume X 302, when the logical volume rule override flag of thefirst type of copy operation is set to the default value of “false”.

FIG. 4 illustrates an exemplary site 400 that has a primary storagecontroller 402 and a secondary storage controller 404, wherein a primaryvolume 406 in the primary storage controller 402 has been consistentlycopied to the secondary volume 408 in the secondary storage controller406. In certain embodiments, the label 410 associated with the secondaryvolume 408 may indicate the identity of the secondary volume, and therules 412 associated with the secondary volume 408 may indicate that thepoint in time copy operation that uses the secondary volume 408 as thetarget is not allowed (shown via reference numeral 414), except in thecase of reverse restore operations, or if the point in time copyoperation's logical volume rule override flag is not set to the defaultvalue of “false”.

Therefore, FIG. 4 illustrates certain embodiments in which point in timecopy operations are restricted from using as the target those volumesthat already store consistently copied data.

FIG. 5 illustrates an exemplary embodiment 500 in which logical volumesC 502 and D 604 are in a consistent copy relationship. If a withdrawcommand 506 that requests withdrawal of logical volume C, logical volumeD, or both logical volumes C and D, is initiated in the computingenvironment 100, then the withdraw command 506 is rejected based on atleast the rules associated with the logical volumes C 502 and D 504.

Therefore, FIG. 5 illustrates certain embodiments in which withdrawcommands cannot be used to break a consistent copy relationship betweentwo logical volumes, unless the logical volume rule override flag in thewithdraw commands are set to override the rules and labels associatedwith the two logical volumes.

FIG. 6 illustrates a first set of exemplary operations that may beperformed by one or more storage controllers 102 a . . . 102 n presentin the computing environment 100.

Control starts at block 600 in which, a plurality of logical volumes 106a . . . 106 p, 108 a . . . 108 q, 110 a . . . 110 r are stored at aplurality of sites 104 a . . . 104 n, wherein in certain embodimentsvolume labels and associated rules may be set corresponding to theplurality of logical volumes 106 a . . . 106 p, 108 a . . . 108 q, 110 a. . . 110 r. A command 200 to execute an operation on a logical volume302 is received (at block 602). In certain embodiments, the logicalvolume 302 is in a copy service relationship with another logicalvolume. In other embodiments, the logical volume 302 is configured formigration of data or disaster recovery or some other operation. Adetermination is made (at block 604) as to whether a rule 304 associatedwith the logical volume 302 permits execution of the operation on thelogical volume. In response to determining (“Yes” branch from block 604)that the rule associated with the logical volume permits execution ofthe operation on the logical volume, the operation is executed (at block606) on the logical volume. Also, in response to determining that therule associated with logical volume does not permit execution of theoperation on the logical volume (“No” branch from block 604), theexecution of the operation on the logical volume is avoided (at block608).

Therefore, FIG. 6 illustrates certain embodiments in which rulesassociated with a logical volume restrict operations that may beperformed on the logical volume.

FIG. 7 illustrates a second set of exemplary operations that may beperformed by one or more storage controllers 102 a . . . 102 n presentin the computing environment 100.

Control starts at block 700 in which, a plurality of logical volumes 106a . . . 106 p, 108 a . . . 108 q, 110 a . . . 110 r are stored at aplurality of sites 104 a . . . 104 n. A command 200 to execute anoperation on a logical volume 302 is received (at block 702).

A determination is made (at block 704) as to whether a parameter 206 ofthe command indicates that the rule associated with the logical volumeis to be overridden by the command. In response to determining that therule associated with the logical volume is to be overridden by thecommand, the operation on the logical volume is executed (at block 706).

Therefore, FIG. 7 illustrates certain embodiments in which a logicalvolume rule override flag's setting may be used to determine whether ornot to override a rule associated with a logical volume.

Certain embodiments may provide a mechanism to set volume labels (volumenames and/or labels, etc.) and to associate rules with these volumelabels. Mechanisms may be provided for a new query to determine avolume's label and associated characteristics. A verbose option may alsoprovide the current copy services relationships for the volume. A bulkoption to not just obtain information for a single specific volume butobtain information for all volumes of a particular label in a subsystemmay also be provided. In certain additional embodiments, new bits forenforcing or overriding the associated rules during copy services anddisaster recovery may be provided. Furthermore, mechanisms for modifyingor clearing the volume label and/or rules may also be provided.

In certain embodiments, the volume label may help a user to understandwhich volumes are being used and copy relationships may be establishedaccordingly. The volume label itself is of value, but because there areso many possible disaster recovery configurations, the meaning of thelabel and the allowed behavior are also stored. For example, when thelabel is created for a volume, a mechanism for associating expectedbehavior and role in disaster recovery algorithms for the volume typeare also created and stored in a rules data structure.

In certain embodiments, rule usage and enforcement are performed oncelogical volume labels and rules are in place. The rule usage andenforcement may also be performed via alternative embodiments in whichlogical volume labels and rules associated with the logical volumelabels are not set and other mechanisms are used for determining therules. In certain other embodiments, the logical volume labels and rulesmay be used for other operations besides rule enforcement.

In certain embodiments, the logical volumes may be labeled prior to anycopy services relationship being set. In other embodiments, the logicalvolume labels and associated rules may be used without any copy servicesrelationship being set. In certain embodiments, the logical volumelabels and associated rules may be used for data migration or disasterrecovery.

In certain embodiments, the logical volumes of interest need not be inany relationship for the enforcement of rules. In certain otherembodiments, the rules may prevent a logical volume from being put intoa relationship in the first place. For example, in an exemplaryembodiment, an exemplary logical volume 0x1000 may have a logical volumelabel indicating that logical volume 0x1000 is to be used as a point intime copy operation's target. If an establish command is received tomake logical volume 0x1000 into a point in time copy operation's source,in certain embodiments the establish command may be rejected.

Additional Embodiment Details

The described operations may be implemented as a method, apparatus orcomputer program product using standard programming and/or engineeringtechniques to produce software, firmware, hardware, or any combinationthereof. Accordingly, aspects of the embodiments may take the form of anentirely hardware embodiment, an entirely software embodiment (includingfirmware, resident software, micro-code, etc.) or an embodimentcombining software and hardware aspects that may all generally bereferred to herein as a “circuit,” “module” or “system.” Furthermore,aspects of the embodiments may take the form of a computer programproduct embodied in one or more computer readable medium(s) havingcomputer readable program code embodied there.

Any combination of one or more computer readable medium(s) may beutilized. The computer readable medium may be a computer readable signalmedium or a computer readable storage medium. A computer readablestorage medium may be, for example, but not limited to, an electronic,magnetic, optical, electromagnetic, infrared, or semiconductor system,apparatus, or device, or any suitable combination of the foregoing. Morespecific examples (a non-exhaustive list) of the computer readablestorage medium would include the following: an electrical connectionhaving one or more wires, a portable computer diskette, a hard disk, arandom access memory (RAM), a read-only memory (ROM), an erasableprogrammable read-only memory (EPROM or Flash memory), an optical fiber,a portable compact disc read-only memory (CD-ROM), an optical storagedevice, a magnetic storage device, or any suitable combination of theforegoing. In the context of this document, a computer readable storagemedium may be any tangible medium that can contain, or store a programfor use by or in connection with an instruction execution system,apparatus, or device.

A computer readable signal medium may include a propagated data signalwith computer readable program code embodied therein, for example, inbaseband or as part of a carrier wave. Such a propagated signal may takeany of a variety of forms, including, but not limited to,electro-magnetic, optical, or any suitable combination thereof. Acomputer readable signal medium may be any computer readable medium thatis not a computer readable storage medium and that can communicate,propagate, or transport a program for use by or in connection with aninstruction execution system, apparatus, or device.

Program code embodied on a computer readable medium may be transmittedusing any appropriate medium, including but not limited to wireless,wireline, optical fiber cable, RF, etc., or any suitable combination ofthe foregoing.

Computer program code for carrying out operations for aspects of thepresent invention may be written in any combination of one or moreprogramming languages, including an object oriented programming languagesuch as Java*, Smalltalk, C++ or the like and conventional proceduralprogramming languages, such as the “C” programming language or similarprogramming languages. The program code may execute entirely on theuser's computer, partly on the user's computer, as a stand-alonesoftware package, partly on the user's computer and partly on a remotecomputer or entirely on the remote computer or server. In the latterscenario, the remote computer may be connected to the user's computerthrough any type of network, including a local area network (LAN) or awide area network (WAN), or the connection may be made to an externalcomputer (for example, through the Internet using an Internet ServiceProvider). *Java is a trademark or registered trademark of SunMicrosystems, Inc.

Aspects of the present invention are described below with reference toflowchart illustrations and/or block diagrams of methods, apparatus(systems) and computer program products according to embodiments of theinvention. It will be understood that each block of the flowchartillustrations and/or block diagrams, and combinations of blocks in theflowchart illustrations and/or block diagrams, can be implemented bycomputer program instructions. These computer program instructions maybe provided to a processor of a general purpose computer, specialpurpose computer, or other programmable data processing apparatus toproduce a machine, such that the instructions, which execute via theprocessor of the computer or other programmable data processingapparatus, create means for implementing the functions/acts specified inthe flowchart and/or block diagram block or blocks.

These computer program instructions may also be stored in a computerreadable medium that can direct a computer, other programmable dataprocessing apparatus, or other devices to function in a particularmanner, such that the instructions stored in the computer readablemedium produce an article of manufacture including instructions whichimplement the function/act specified in the flowchart and/or blockdiagram block or blocks.

The computer program instructions may also be loaded onto a computer,other programmable data processing apparatus, or other devices to causea series of operational steps to be performed on the computer, otherprogrammable apparatus or other devices to produce a computerimplemented process such that the instructions which execute on thecomputer or other programmable apparatus provide processes forimplementing the functions/acts specified in the flowchart and/or blockdiagram block or blocks.

FIG. 8 illustrates a block diagram that shows certain elements that maybe included in a system 800 in accordance with certain embodiments. Thesystem 800 may comprise the storage controllers 102 a . . . 102 n andmay include a circuitry 802 that may in certain embodiments include atleast a processor 804. The system 800 may also include a memory 806(e.g., a volatile memory device), and storage 808. The storage 808 mayinclude a non-volatile memory device (e.g., EEPROM, ROM, PROM, RAM,DRAM, SRAM, flash, firmware, programmable logic, etc.), magnetic diskdrive, optical disk drive, tape drive, etc. The storage 808 may comprisean internal storage device, an attached storage device and/or a networkaccessible storage device. The system 800 may include a program logic810 including code 812 that may be loaded into the memory 806 andexecuted by the processor 804 or circuitry 802. In certain embodiments,the program logic 810 including code 812 may be stored in the storage808. In certain other embodiments, the program logic 810 may beimplemented in the circuitry 802. Therefore, while FIG. 8 shows theprogram logic 810 separately from the other elements, the program logic810 may be implemented in the memory 806 and/or the circuitry 802.

In certain embodiments, the storage controllers 102 a . . . 102 n maycomprise cloud component parts included in a cloud computingenvironment. In the cloud computing environment the systems architectureof the hardware and software components involved in the delivery ofcloud computing may involve a plurality of cloud componentscommunicating with each other.

Certain embodiments may be directed to a method for deploying computinginstruction by a person or automated processing integratingcomputer-readable code into a computing system, wherein the code incombination with the computing system is enabled to perform theoperations of the described embodiments.

The terms “an embodiment”, “embodiment”, “embodiments”, “theembodiment”, “the embodiments”, “one or more embodiments”, “someembodiments”, and “one embodiment” mean “one or more (but not all)embodiments of the present invention(s)” unless expressly specifiedotherwise.

The terms “including”, “comprising”, “having” and variations thereofmean “including but not limited to”, unless expressly specifiedotherwise.

The enumerated listing of items does not imply that any or all of theitems are mutually exclusive, unless expressly specified otherwise.

The terms “a”, “an” and “the” mean “one or more”, unless expresslyspecified otherwise.

Devices that are in communication with each other need not be incontinuous communication with each other, unless expressly specifiedotherwise. In addition, devices that are in communication with eachother may communicate directly or indirectly through one or moreintermediaries.

A description of an embodiment with several components in communicationwith each other does not imply that all such components are required. Onthe contrary a variety of optional components are described toillustrate the wide variety of possible embodiments of the presentinvention.

Further, although process steps, method steps, algorithms or the likemay be described in a sequential order, such processes, methods andalgorithms may be configured to work in alternate orders. In otherwords, any sequence or order of steps that may be described does notnecessarily indicate a requirement that the steps be performed in thatorder. The steps of processes described herein may be performed in anyorder practical. Further, some steps may be performed simultaneously.

When a single device or article is described herein, it will be readilyapparent that more than one device/article (whether or not theycooperate) may be used in place of a single device/article. Similarly,where more than one device or article is described herein (whether ornot they cooperate), it will be readily apparent that a singledevice/article may be used in place of the more than one device orarticle or a different number of devices/articles may be used instead ofthe shown number of devices or programs. The functionality and/or thefeatures of a device may be alternatively embodied by one or more otherdevices which are not explicitly described as having suchfunctionality/features. Thus, other embodiments of the present inventionneed not include the device itself.

At least certain operations that may have been illustrated in thefigures show certain events occurring in a certain order. In alternativeembodiments, certain operations may be performed in a different order,modified or removed. Moreover, steps may be added to the above describedlogic and still conform to the described embodiments. Further,operations described herein may occur sequentially or certain operationsmay be processed in parallel. Yet further, operations may be performedby a single processing unit or by distributed processing units.

The foregoing description of various embodiments of the invention hasbeen presented for the purposes of illustration and description. It isnot intended to be exhaustive or to limit the invention to the preciseform disclosed. Many modifications and variations are possible in lightof the above teaching. It is intended that the scope of the invention belimited not by this detailed description, but rather by the claimsappended hereto. The above specification, examples and data provide acomplete description of the manufacture and use of the composition ofthe invention. Since many embodiments of the invention can be madewithout departing from the spirit and scope of the invention, theinvention resides in the claims hereinafter appended.

What is claimed is:
 1. A system comprising: a memory; and a processorcoupled to the memory, wherein the processor performs operations, theoperations comprising: storing a plurality of logical volumes, at aplurality of sites; receiving, a point in time copy command to executean operation on a logical volume, wherein the point in time copy commandhas a first parameter that indicates a source logical volume, a secondparameter that indicates a target logical volume, and a third parameterthat is a logical volume rule override flag that indicates whether ornot a rule associated with the logical volume is to be overridden by thepoint in time copy command; in response to determining from the logicalvolume rule override flag that the rule associated with the logicalvolume is to be overridden by the point in time copy command, executingthe operation on the logical volume irrespective of any restrictionplaced by the rule on the logical volume; in response to determiningthat the logical volume override flag is set to a default value toindicate that the rule associated with the logical volume is not to beoverridden by the point in time copy command, processing the ruleassociated with the logical volume to determine whether the operation isto be executed on the logical volume; determining, whether the ruleassociated with the logical volume permits execution of the operation onthe logical volume, wherein the rule is stored in a logical volume rulesdata structure; in response to determining that the rule associated withthe logical volume permits execution of the operation on the logicalvolume, executing the operation on the logical volume; and in responseto determining that the rule associated with logical volume does notpermit execution of the operation on the logical volume, avoidingexecuting the operation on the logical volume.
 2. The system of claim 1,wherein: the rule associated with the logical volume restricts a copyoperation to be performed on the logical volume to overwrite the logicalvolume if the logical volume stores a consistent copy of another logicalvolume; and a label associated with the logical volume identifies thelogical volume.
 3. The system of claim 1, wherein the logical volume isa first logical volume that is in a consistent copy service relationshipwith a second logical volume; wherein a withdraw command requestswithdrawal of at least the first or the second logical volume from theconsistent copy service relationship; and rejecting the withdrawcommand, in response to interpreting rules associated with the first orthe second logical volume.
 4. The system of claim 1, wherein prior toreceiving the point in time copy command to execute the operation on thelogical volume, performing: setting a volume label for the logicalvolume; and associating the rule with the volume label.
 5. The system ofclaim 1, wherein the logical volume is in a copy service relationshipwith another logical volume.
 6. The system of claim 1, wherein thelogical volume is configured to perform migration of data or disasterrecovery.
 7. A computer program product, the computer program productcomprising: a computer readable storage device having computer readableprogram code embodied therewith, the computer readable program codeconfigured to perform operations, the operations comprising: storing aplurality of logical volumes, at a plurality of sites; receiving, apoint in time copy command to execute an operation on a logical volume,wherein the point in time copy command has a first parameter thatindicates a source logical volume, a second parameter that indicates atarget logical volume, and a third parameter that is a logical volumerule override flag that indicates whether or not a rule associated withthe logical volume is to be overridden by the point in time copycommand; in response to determining from the logical volume ruleoverride flag that the rule associated with the logical volume is to beoverridden by the point in time copy command, executing the operation onthe logical volume irrespective of any restriction placed by the rule onthe logical volume; in response to determining that the logical volumeoverride flag is set to a default value to indicate that the ruleassociated with the logical volume is not to be overridden by the pointin time copy command, processing the rule associated with the logicalvolume to determine whether the operation is to be executed on thelogical volume; determining, whether the rule associated with thelogical volume permits execution of the operation on the logical volume,wherein the rule is stored in a logical volume rules data structure; inresponse to determining that the rule associated with the logical volumepermits execution of the operation on the logical volume, executing theoperation on the logical volume; and in response to determining that therule associated with logical volume does not permit execution of theoperation on the logical volume, avoiding executing the operation on thelogical volume.
 8. The computer program product of claim 7, wherein: therule associated with the logical volume restricts a copy operation to beperformed on the logical volume to overwrite the logical volume if thelogical volume stores a consistent copy of another logical volume; and alabel associated with the logical volume identifies the logical volume.9. The computer program product of claim 7, wherein the logical volumeis a first logical volume that is in a consistent copy servicerelationship with a second logical volume; wherein a withdraw commandrequests withdrawal of at least the first or the second logical volumefrom the consistent copy service relationship; and rejecting thewithdraw command, in response to interpreting rules associated with thefirst or the second logical volume.
 10. The computer program product ofclaim 7, wherein prior to receiving the point in time copy command toexecute the operation on the logical volume, performing: setting avolume label for the logical volume; and associating the rule with thevolume label.
 11. The computer program product of claim 7, wherein thelogical volume is in a copy service relationship with another logicalvolume.
 12. The computer program product of claim 7, wherein the logicalvolume is configured to perform migration of data or disaster recovery.13. A storage controller coupled to a plurality of other storagecontrollers at a plurality of sites, the storage controller comprising:a memory; and a processor coupled to the memory, wherein the processorperforms operations, the operations comprising: storing a plurality oflogical volumes, at the plurality of sites; receiving, a point in timecopy command to execute an operation on a logical volume, wherein thepoint in time copy command has a first parameter that indicates a sourcelogical volume, a second parameter that indicates a target logicalvolume, and a third parameter that is a logical volume rule overrideflag that indicates whether or not a rule associated with the logicalvolume is to be overridden by the point in time copy command; inresponse to determining from the logical volume rule override flag thatthe rule associated with the logical volume is to be overridden by thepoint in time copy command, executing the operation on the logicalvolume irrespective of any restriction placed by the rule on the logicalvolume; in response to determining that the logical volume override flagis set to a default value to indicate that the rule associated with thelogical volume is not to be overridden by the point in time copycommand, processing the rule associated with the logical volume todetermine whether the operation is to be executed on the logical volume;determining, whether the rule associated with the logical volume permitsexecution of the operation on the logical volume, wherein the rule isstored in a logical volume rules data structure; in response todetermining that the rule associated with the logical volume permitsexecution of the operation on the logical volume, executing theoperation on the logical volume; and in response to determining that therule associated with logical volume does not permit execution of theoperation on the logical volume, avoiding executing the operation on thelogical volume.
 14. The storage controller of claim 13, wherein: therule associated with the logical volume restricts a copy operation to beperformed on the logical volume to overwrite the logical volume if thelogical volume stores a consistent copy of another logical volume; and alabel associated with the logical volume identifies the logical volume.15. The storage controller of claim 13, wherein the logical volume is afirst logical volume that is in a consistent copy service relationshipwith a second logical volume; wherein a withdraw command requestswithdrawal of at least the first or the second logical volume from theconsistent copy service relationship; and rejecting the withdrawcommand, in response to interpreting rules associated with the first orthe second logical volume.
 16. The storage controller of claim 13,wherein prior to receiving the point in time copy command to execute theoperation on the logical volume, performing: setting a volume label forthe logical volume; and associating the rule with the volume label. 17.The storage controller of claim 13, wherein the logical volume is in acopy service relationship with another logical volume.
 18. The storagecontroller of claim 13, wherein the logical volume is configured toperform migration of data or disaster recovery.